Not really enough info there to say whether the particular strikers you have found are good or not.
I once saw Mors Kochanski demonstrate striking sparks off a particularly cheap brand of all hard carbon steel hacksaw blade. From standing, he had sparks hitting the floor. I have had no luck finding similar blades. I just use a bit of file with the teeth ground off one side.
I would be interested to hear if there is any flint within dozens of miles of your Derbyshire moorland. The geological survey maps for the UK are interesting stuff. Flint is present in places that are not listed, but typically they are areas that do state that they have clay soils, such as south Leicestershire.
The Geology of Britain viewer has been designed to help the general public explore the local geology around where they live.
mapapps.bgs.ac.uk
Do you have any friends or family that you could tap to bring you a lump of their local stone?
There are places that do not have flint. That was why it was a stone-age trade good.
Chris